One Marine was killed and 21 others hurt Sunday when a helicopter at Bellows Air Force Station experienced a “hard landing,” the U.S. military said Sunday.

Crash at Hawaii Air Force

The incident took place just as the U.S. Marine Corps and Navy this week were hosting defense leaders from around the Pacific.

An MV-22 Osprey from the 15th Marine Expeditionary Unit crashed during a training exercise around 11:40 a.m. local time.

Twenty-two people were aboard the aircraft, including 21 Marines and one Navy corpsman assigned to the unit, spokesman Capt. Brian Block said in an email.

The injuries ranged from critical to minor, Marine Corps Forces Pacific spokesman Capt. Alex Lim said.